Ultrasound, mammography, magnetic resonance imaging, and other medical imaging modalities are widely used to identify suspicious lesions within the body of a patient. Historically, when a suspicious lesion is located within the body of a patient, a guide wire was inserted by the physician to mark the location of the lesion to enable a surgeon to locate the lesion for removal. The guide wires typically include barbs or hooks at their forward ends to securely anchor the guide within the target tissue.
A problem with such guide wires, however, is that it is sometimes difficult for the surgeon to locate the forward end of the guide wire. While tugging on the guide wire will cause movement at the forward end which the surgeon can visually identify, the tugging action can also dislodge the guide wire from the target tissue. Accordingly, another method of locating the forward end of a guide wire was needed.
To address this problem, the prior art discloses a guide wire fabricated from an optical fiber. Hooks were affixed to the forward end of the optical fiber to anchor the tip of the fiber in the target tissue. The free end of the optical fiber was hooked up to a small laser, and a beam of light was directed through the fiber. A diffuser tip at the forward end of the guide wire created a point of light which could easily be visualized by a surgeon through several centimeters of tissue, thereby facilitating the location of the forward end of the guide wire. U.S. Pat. No. 5,782,771 to Hussman and an article entitled Optical Breast Lesion Localization Fiber: Preclinical Testing of a New Device from the September 1996 issue of RADIOLOGY describe the optical fiber localization device in detail.
While this prior art device represents an improvement in terms of locating the forward end of the guide wire without dislodging the guide wire from the tissue, there are significant structural problems inherent in the design of the device. Specifically, the optical fiber incorporates a stepdown portion at the forward tip of the fiber to diffuse the transmitted light. This step-down portion, however, also creates a structural weakness that is exacerbated by the hooks being mounted to the reduced portion. In short, any significant torque on the hooks can cause the tip of the optical fiber to break off.
Thus there is a need for an optical fiber tissue localization device which better resists breakage in response to torque exerted by the hooks.
There is a further need for an optical fiber tissue localization device which meets the foregoing needs while being inexpensive to manufacture.